Back-end processing system for metal recovery from municipal solid waste incineration fly ash

Abstract

The application provides a back-end processing system for metal recovery in household garbage incineration fly ash, which comprises a reaction kettle in communication with a leaching solution storage tank, a dosing unit in communication with the reaction kettle and capable of adding zinc into the reaction kettle, a filter in communication with the reaction kettle, an extraction unit in communication with the filter, a sewage treatment device in communication with the extraction unit, an electrolysis unit in communication with the extraction unit, and a grinding device located in the electrolysis unit. The filter has a slag outlet for leading out the mixture of copper, cadmium and lead, and has a liquid outlet for leading out the zinc chloride solution and in communication with the extraction unit. The grinding device can grind the part of blocky zinc elements obtained by the electrolysis unit to be sent into the dosing unit again. The back-end processing system for metal recovery in household garbage incineration fly ash provided by the application has simple processing steps, does not need a large amount of chemical reagents, is convenient for processing of a large amount of fly ash or filtrate, can effectively ensure the zinc recovery efficiency, and has high practicability.

Description

Technical Field

[0001] This invention belongs to the field of municipal solid waste incineration fly ash reuse technology, specifically relating to a back-end processing system for metal recovery from municipal solid waste incineration fly ash. Background Technology

[0002] Municipal solid waste refers to the fixed waste generated by people in their daily lives or in activities that provide services for daily life. The common method for treating municipal solid waste is incineration, which can generate electricity and achieve energy recovery. However, the incineration process produces a large amount of fly ash, which contains high concentrations of heavy metals such as Pb, Cd, Cu, and Zn, and is classified as hazardous waste. These heavy metals are mostly deposited on the surface of fly ash particles and can dissolve at any time. If not properly disposed of, these heavy metals can leach from the fly ash and pollute groundwater and soil. From the perspective of long-term environmental safety, the heavy metals in fly ash can be utilized as resources, which is both a form of resource conservation and does not pose a potential threat to the environment. Hydrochloric acid is commonly used as a chemical reagent for leaching heavy metals Cu, Zn, Cd, and Pb from fly ash. The reaction between the heavy metals and the chemical reagent promotes the dissolution of heavy metals in the fly ash, resulting in residual ash with low heavy metal content and a high-concentration heavy metal leachate. The collected leachate is then treated to ensure the collection of Pb, Cd, Cu, and Zn.

[0003] In existing technologies, the treatment of leachate typically involves first extracting copper ions with a mixture of 5-nonylsalicylaldehyde oxime and kerosene to obtain an aqueous phase and a copper-loaded organic phase. Then, zinc ions in the aqueous phase are extracted with a mixture of dithiophosphonic acid 572 and kerosene, yielding a residual aqueous phase and a zinc-loaded organic phase. Copper in the copper-loaded organic phase is collected by sulfuric acid stripping, and zinc in the zinc-loaded organic phase is collected by nitric acid stripping. Finally, lead and cadmium in the residual aqueous phase are removed using carboxymethyl cellulose-modified nano-zero-valent iron. This method requires large amounts of extractant and chemical reagents, making it costly, complex, and impractical for large-scale heavy metal recovery from fly ash. Summary of the Invention

[0004] This invention provides a back-end treatment system for metal recovery from fly ash in municipal solid waste incineration, aiming to solve the problem of poor practicality of existing fly ash back-end leachate recovery and treatment methods.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a back-end treatment system for metal recovery from fly ash of municipal solid waste incineration is provided, including a reaction vessel connected to a leachate storage tank, a dosing unit connected to the reaction vessel for adding zinc metal to the reaction vessel, a filter connected to the reaction vessel, an extraction unit connected to the filter, a wastewater treatment device connected to the extraction unit, an electrolysis unit connected to the extraction unit, and a grinding device located in the electrolysis unit and the grinding device.

[0006] The filter has a slag outlet for discharging a mixture of copper, cadmium and lead, and a liquid outlet for discharging a zinc chloride solution and communicating with the extraction unit.

[0007] The grinding equipment is used to grind a portion of the blocky elemental zinc obtained from the electrolysis unit, so as to feed it back into the dosing unit.

[0008] In one possible implementation, the grinding equipment is a ball mill.

[0009] In one possible implementation, the filter includes a support frame, a housing, a filter element structure, a sliding sleeve, and a drive structure; the housing is mounted on the support frame and has a receiving cavity and a liquid inlet communicating with the receiving cavity; the top of the housing is provided with multiple sets of spaced-apart drainage modules, with the spacing direction of each drainage module defined as a first direction and the horizontal direction perpendicular to the first direction defined as a second direction, each set of drainage modules including multiple liquid transfer structures spaced-apart along the second direction; each liquid transfer structure is connected to the extraction unit through a liquid transfer pipeline; and each liquid transfer structure is provided with a one-way air inlet structure; multiple filter element structures are provided, each filter element structure corresponding one-to-one with each liquid transfer structure, each filter element structure... The filter element structure is slidably disposed vertically within the accommodating cavity, with its top end extending into the corresponding liquid transfer structure. Each filter element structure has a liquid outlet that communicates with the liquid transfer port on the liquid transfer structure. Multiple sliding sleeves are provided, each slidably disposed at the bottom of the housing and corresponding to one of the liquid transfer structures. The top end of each sliding sleeve is located within the accommodating cavity, and the bottom end is located below the housing. A sealing structure is provided at the bottom end of each sliding sleeve. Multiple drive structures are provided, each corresponding to one of the drainage modules. Each drive structure is connected to the bottom of the multiple sliding sleeves corresponding to each drainage module, and is used to drive each sliding sleeve to move up and down.

[0010] Each of the driving structures drives the corresponding sliding sleeves to move upwards and fit over the outside of the corresponding filter element structure. Subsequently, each sliding sleeve abuts against the annular plate on the corresponding filter element structure and pushes the filter element structure upwards to disconnect the liquid outlet and liquid transmission outlet. At the same time, the one-way air inlet structure is opened to backwash the filter element structure.

[0011] In one possible implementation, each of the liquid transfer structures includes a fixed cylinder and a cover plate; the fixed cylinder is fixed to the top of the housing and has a cylindrical cavity arranged vertically and communicating with the receiving cavity; the liquid transfer port is located on the side wall of the fixed cylinder; the cover plate is detachably connected to the top of the fixed cylinder and the cover plate is provided with an air hole communicating with the one-way air inlet structure.

[0012] In one possible implementation, each filter element structure includes a slide cylinder, a filter cylinder, a top cover, a liquid extraction tube, and a spring; the slide cylinder is slidably connected to the top of the housing in a vertical direction, with its top end extending into the corresponding cylinder cavity and its bottom end located in the receiving cavity; the annular plate is sleeved on the bottom of the slide cylinder; the liquid outlet is located on the side wall of the slide cylinder; the filter cylinder is arranged in a vertical direction, with its top end fixedly connected to the bottom end of the slide cylinder, and the filter cylinder and the slide cylinder combined to form a filtration cavity; the top cover is fixedly disposed on the top of the slide cylinder, and the top cover has multiple air holes and a pin corresponding to the one-way air inlet structure; the liquid extraction tube is disposed in the filtration cavity, with its top end connected to the slide cylinder and communicating with the liquid outlet, and its bottom end extending to the bottom end of the filtration cavity; the spring is disposed in the cylinder cavity, with its top end abutting against the cover plate and its bottom end abutting against the top cover.

[0013] In one possible implementation, each of the unidirectional air intake structures includes an air intake pipe, a sealing ball, and an elastic element; the air intake pipe is fixed to the cover plate, and a fixing ring is provided in the air intake pipe at a distance from the cover plate; the sealing ball is disposed between the fixing ring and the cover plate; the elastic element is disposed between the fixing ring and the cover plate and abuts against the sealing ball, for continuously pushing the sealing ball so that the sealing ball keeps blocking the air hole.

[0014] In one possible implementation, each of the sealing structures includes a baffle and a telescopic structure; the baffle is hinged to the bottom end of the sliding sleeve, and the baffle is provided with a fixed pull rod, one end of which extends obliquely; the fixed end of the telescopic structure is hinged to the sliding sleeve, and the telescopic end is hinged to the extended end of the fixed pull rod, for driving the baffle to pitch and rotate.

[0015] In one possible implementation, each of the drive structures includes a rectangular frame and a hydraulic cylinder; the rectangular frame has a rectangular opening through which the corresponding sliding sleeve passes, the length direction of the rectangular opening being arranged along the second direction; two hydraulic cylinders are provided, the two hydraulic cylinders being respectively arranged on both sides of the housing along the second direction, and both being arranged on the support frame, the telescopic end of each hydraulic cylinder being fixedly connected to the rectangular frame;

[0016] Each of the sliding sleeves has a limiting groove at its bottom that limits the rectangular frame along the vertical direction.

[0017] In one possible implementation, the filter further includes a receiving hopper located below each of the sliding sleeves.

[0018] In this method, metallic zinc is added to the reactor via a dosing unit to displace the filtrate, ensuring the simultaneous removal of cadmium, lead, and copper ions. Cadmium, lead, and copper are then separated via a filter. Simultaneously, extraction and electrolysis units ensure zinc recovery. This method is simple, requires no large quantities of chemical reagents, facilitates the processing of large quantities of fly ash or filtrate, effectively guarantees zinc recovery efficiency, and is highly practical. Furthermore, the final obtained elemental zinc can be ground and reused, achieving circular production. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the back-end processing system for metal recovery from fly ash of municipal solid waste incineration, provided in an embodiment of the present invention.

[0020] Figure 2 This is a schematic diagram of the filter structure of the back-end treatment system for metal recovery from fly ash of municipal solid waste incineration provided in an embodiment of the present invention;

[0021] Figure 3 This is a cross-sectional view of the filter structure of the back-end treatment system for metal recovery from fly ash of municipal solid waste incineration provided in an embodiment of the present invention;

[0022] Figure 4 for Figure 3 The diagram shows a cross-sectional view along line AA of the back-end processing system for metal recovery from fly ash of municipal solid waste incineration. Figure 1 ;

[0023] Figure 5 for Figure 3 The diagram shows an enlarged view of section B of the back-end processing system for metal recovery from municipal solid waste incineration fly ash; (the liquid transfer port and liquid discharge port are connected).

[0024] Figure 6 for Figure 3 The diagram shows an enlarged view of section B of the back-end processing system for metal recovery from fly ash in municipal solid waste incineration. Figure 2 (When the slide moves upward, the liquid transfer port and the liquid discharge port are disconnected.)

[0025] Explanation of reference numerals in the attached figures:

[0026] 10. Reactor;

[0027] 20. Dosing unit;

[0028] 30. Filter; 31. Support frame; 32. Housing; 321. Receptacle; 322. Liquid inlet; 323. Liquid outlet; 33. Filter element structure; 331. Sliding cylinder; 332. Filter cartridge; 333. Top cover; 334. Suction pipe; 335. Spring; 336. Annular plate; 337. Pin; 337. Liquid outlet; 34. Sliding sleeve; 35. Drive structure; 351. Rectangular frame; 352. Hydraulic cylinder; 36. Liquid transfer structure; 361. Fixed cylinder; 362. Cover plate; 363. Liquid transfer port; 37. One-way air inlet structure; 371. Air inlet pipe; 372. Sealing ball; 373. Elastic element; 38. Sealing structure; 381. Baffle; 382. Telescopic structure; 39. Receiving hopper;

[0029] 40. Extraction unit;

[0030] 50. Wastewater treatment equipment;

[0031] 60. Electrolysis unit;

[0032] 70. Grinding equipment. Detailed Implementation

[0033] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0034] Please refer to the following: Figure 1 The following describes the back-end processing system for metal recovery from municipal solid waste incineration fly ash provided by the present invention. The back-end processing system for metal recovery from municipal solid waste incineration fly ash includes a reactor 10 connected to a leachate storage tank, a dosing unit 20 connected to the reactor 10 for adding zinc metal, a filter 30 connected to the reactor 10, an extraction unit 40 connected to the filter 30, a wastewater treatment device 50 connected to the extraction unit 40, an electrolysis unit 60 connected to the extraction unit 40, and a grinding device 70 located within the electrolysis unit 60.

[0035] Specifically, the filter 30 has a slag outlet for discharging a mixture of copper, cadmium and lead, and a liquid outlet for discharging a zinc chloride solution and communicating with the extraction unit 40.

[0036] Specifically, the grinding equipment 70 can grind some of the blocky zinc obtained by the electrolysis unit 60 and then feed it back into the dosing unit 20.

[0037] The back-end processing system for metal recovery from municipal solid waste incineration fly ash provided in this embodiment operates on the following principle: the filtrate collected in the leachate storage tank is introduced into the reaction vessel 10. Zinc powder is then added through the dosing unit 20, allowing the zinc powder to act as a reducing agent and react fully with the filtrate in the reaction vessel 10, resulting in a mixture of cadmium, lead, copper, and zinc chloride solution. This mixture is then filtered through a filter 30 to obtain cement containing cadmium, lead, and copper. The resulting hydrogen chloride solution subsequently enters the extraction unit 40.

[0038] The filtrate entering the extraction unit 40 mainly contains zinc ions and some other metal ions. To avoid interference from other metal ions on zinc ion electrolysis (electrodeposition), the filtrate needs to be washed. Since the complexation strength of zinc ions is pH-dependent, at low pH, 99.5% of Zn is extracted by the organic phase. Therefore, the zinc ions can be separated in the extraction unit by adding an extractant. The resulting aqueous phase enters the wastewater treatment equipment 50 for further treatment. The organic phase loaded with zinc chloride generates a zinc sulfate solution at the tail end of the extraction unit 40 by adding sulfuric acid. This zinc sulfate solution then enters the electrolysis unit 60, where elemental zinc plates or ingots are obtained through electrolysis. A portion of the obtained zinc plates or ingots is then added to the grinding equipment 70 and ground into powder, before being added to the dosing unit 20 for recycling.

[0039] The back-end processing system for metal recovery from municipal solid waste incineration fly ash provided in this embodiment, compared with the prior art, adds metallic zinc to the reactor 10 through the dosing unit 20 to replace the filtrate in the reactor 10, ensuring the simultaneous removal of cadmium, lead, and copper ions. Furthermore, cadmium, lead, and copper are separated by the filter 30, and zinc recovery is ensured by the extraction unit 40 and the electrolysis unit 60. This method has simple processing steps, requires no large amounts of chemical reagents, facilitates the processing of large quantities of fly ash or filtrate, effectively guarantees zinc recovery efficiency, and is highly practical. In addition, the final obtained elemental zinc can be ground by the grinding equipment 70 for continued use, achieving circular production.

[0040] In this embodiment, the reactor 10, the dosing unit 20, the extraction unit 40, and the wastewater treatment unit are all existing technologies and will not be described in detail here.

[0041] In some embodiments, the grinding apparatus 70 described above may employ, for example... Figure 1 The structure shown. See also Figure 1 The grinding equipment 70 is a ball mill.

[0042] The ball mill has the advantages of high efficiency, uniformity, wide applicability, easy operation and maintenance, and strong controllability. It can ensure that the zinc blocks or zinc granules obtained by the electrolysis unit 60 are ground to ensure that the reagent added by the dosing unit 20 is zinc powder, which can improve the reaction rate of the reactor 10.

[0043] In some embodiments, the filter 30 described above may employ, for example... Figures 2 to 4 The structure shown. See also Figures 2 to 4 The filter 30 includes a support frame 31, a housing 32, a filter element structure 33, a sliding sleeve 34, and a drive structure 35. The housing 32 is mounted on the support frame 31 and has a receiving cavity 321 and a liquid inlet 322 communicating with the receiving cavity 321. The top of the housing 32 is provided with multiple sets of spaced-apart drainage modules. The spacing direction of each drainage module is defined as a first direction, and the horizontal direction perpendicular to the first direction is defined as a second direction. Each set of drainage modules includes multiple liquid transfer structures 36 spaced-apart along the second direction. Each liquid transfer structure 36 is connected to the extraction unit 40 through a liquid transfer pipeline. Each liquid transfer structure 36 is also provided with a one-way air inlet structure 37. Multiple filter element structures 33 are provided, each corresponding to a liquid transfer structure 36. Each filter element structure 33 is slidably disposed in the receiving cavity 321 along the vertical direction, with its top end extending into the corresponding top liquid transfer structure 36. The filter element structure 33 has a liquid outlet 337 that can communicate with the liquid transfer port 363 on the liquid transfer structure 36. Multiple sliding sleeves 34 are provided, each slidably disposed at the bottom end of the housing 32 and corresponding to a liquid transfer structure 36. The top end of each sliding sleeve 34 is located in the receiving cavity 321, and the bottom end is located below the housing 32. The bottom end of the sliding sleeve 34 is provided with a sealing structure 38. Multiple drive structures 35 are provided, each corresponding to a group of drainage modules. Each drive structure 35 is connected to the bottom of the multiple sliding sleeves 34 corresponding to each group of drainage modules, and can drive the sliding sleeves 34 to move up and down.

[0044] Specifically, each drive structure 35 drives the corresponding sliding sleeves 34 to move upward and fit over the outside of the corresponding filter element structure 33. Then, each sliding sleeve 34 abuts against the annular plate 336 on the corresponding filter element structure 33 and pushes the filter element structure 33 upward to disconnect the liquid outlet 337 and the liquid transmission outlet 363. At the same time, the one-way air intake structure 37 is opened to backwash the filter element structure 33.

[0045] Since filter 30 uses a filter element structure 33, after prolonged filtration, a large amount of filter cake will adhere to the outer surface of the filter element, forming a shell. The conventional approach is to shut down the system, drain the mixed liquid from the containment chamber 321, and then clean the filter element structure 33 through backwashing. Because this requires shutting down the system, the continuity of filtration cannot be guaranteed, and the cleaning cycle is too short, severely reducing the overall system's processing efficiency.

[0046] In this embodiment, the housing 32 is supported by the support frame 31 and is suspended in mid-air. The filter element structures 33 inside the housing 32 correspond to the liquid transfer structures 36 and are connected via liquid inlets 337 and liquid transfer outlets 363. This structure ensures that the filtrate within the filter element structure 33 is introduced into the liquid transfer pipeline through the liquid inlets 337 and liquid transfer outlets 363, and then enters the extraction unit 40. The filter element structures 33 are slidable, and multiple sliding sleeves 34, each corresponding to a filter element, are provided at the bottom of the housing 32. These sliding sleeves 34 can move up and down under the drive of the drive structure 35.

[0047] The specific work process is as follows:

[0048] As the sliding sleeve 34 moves upward, it abuts against the annular plate 336 on the filter element structure 33, simultaneously enclosing the corresponding filter element structure 33. At this point, the filter element structure 33 located inside the sliding sleeve 34 and the annular plate 336 becomes independent of the receiving cavity 321. The mixture inside the sliding sleeve 34 is filtered through the filter element structure 33. After the mixture inside the sliding sleeve 34 is further filtered, only the filter residue shell attached to the outer surface of the filter element structure 33 remains inside the sliding sleeve 34. At this time, the driving structure 35 continues to drive the sliding sleeve 34 upward, and the annular plate 336 pushes the filter element structure 33 upward, causing the liquid transfer port 363 and the liquid discharge port 337 to become misaligned, thus disconnecting their connection. During this process, the filter element structure 33 will trigger the one-way air intake structure 37 on the drainage structure, causing the one-way air intake structure 37 to open. Subsequently, the air injection module connected to the one-way air intake structure 37 will inject gas into the filter element structure 33, performing a reverse flushing of the filter element structure 33, causing the filter cake adhering to the filter element surface to detach, and simultaneously cleaning the filter pores. Then, through the sealing structure 38 provided at the bottom end of the sliding sleeve 34, the sliding sleeve 34 is opened at the bottom end, allowing the filter cake to be discharged to the outside.

[0049] After the filter residue is discharged, the bottom end of the sliding sleeve 34 is sealed by the sealing structure 38. Then, the sliding sleeve 34 is driven downward by the driving structure 35. At the same time, the filter element structure 33 also descends to connect with the liquid outlet 337 and the liquid transfer outlet 363, and the one-way air inlet structure 37 is automatically sealed. Subsequently, the sliding sleeve 34 descends to the lowest point, and the filter element structure 33 continues to perform filtration.

[0050] The drive structure 35 will simultaneously drive multiple sliding sleeves 34 to move vertically, thereby enabling the simultaneous cleaning of multiple filter element structures 33 and improving cleaning efficiency.

[0051] Regarding the air injection module, it may include multiple connecting pipes communicating with each unidirectional air intake structure 37, a main pipe communicating with each connecting pipe, and a booster pump; these are all existing technologies and will not be described in detail here. Of course, in this embodiment, the air injection module can also be backflushed by injecting water.

[0052] Regarding the liquid transfer pipeline, it can ensure that the branch pipes and the main pipe connected to the extraction unit 40 are connected. Multiple branch pipes correspond to multiple liquid transfer structures 36 respectively and are all connected to the main pipe. A pressure pump can be installed on the main pipe. This technology is existing technology and is well known to those skilled in the art, so it will not be described in detail here.

[0053] In this embodiment, a drain port 323 is also provided at the bottom of the housing 32 to ensure that the remaining mixture in the accommodating cavity 321 is discharged.

[0054] In some embodiments, the liquid transfer structure 36 described above can be as follows: Figure 5 The structure shown. See also Figure 5 Each liquid transfer structure 36 includes a fixed cylinder 361 and a cover plate 362. The fixed cylinder 361 is fixed to the top of the housing 32 and has a cylindrical cavity arranged vertically and communicating with the receiving cavity 321. The liquid transfer port 363 is located on the side wall of the fixed cylinder 361. The cover plate 362 is detachably connected to the top of the fixed cylinder 361, and the cover plate 362 is provided with an air hole communicating with the one-way air inlet structure 37.

[0055] The fixed cylinder 361 is fixed to the top of the housing 32 and sealed by the cover plate 362. This structure facilitates the disassembly and replacement of the filter element structure 33. The cover plate 362 and the fixed cylinder 361 can be connected by a flange. The liquid transfer port 363 on the fixed cylinder 361 can be directly connected to and communicate with the liquid transfer pipeline.

[0056] An upper sliding hole corresponding to the cylindrical cavity needs to be opened at the top of the housing 32, and an annular seal is provided on the inner wall of the upper sliding hole, as shown in the figure. Figure 5 and Figure 6 .

[0057] In some embodiments, the filter element structure 33 described above can be adopted as follows: Figures 3 to 6 The structure shown. See also Figures 3 to 6Each filter element structure 33 includes a slide cylinder 331, a filter cylinder 332, a top cover 333, a liquid extraction tube 334, and a spring 335. The slide cylinder 331 is slidably connected to the top of the housing 32 in a vertical direction, with its top end extending into the corresponding cylindrical cavity and its bottom end located in the receiving cavity 321. An annular plate 336 is fitted onto the bottom of the slide cylinder 331. A liquid outlet 337 is located on the side wall of the slide cylinder 331. The filter cylinder 332 is arranged in a vertical direction, with its top end fixedly connected to the bottom end of the slide cylinder 331. The filter cylinder 332 and the slide cylinder 331 together form a filtration cavity. The top cover 333 is fixed to the top of the slide cylinder 331 and has multiple air holes and a pin 337 corresponding to the one-way air inlet structure 37. A liquid extraction tube 334 is installed in the filter chamber. The top end of the liquid extraction tube 334 is connected to the slide tube 331 and communicates with the liquid outlet 337. The bottom end of the liquid extraction tube 334 extends to the bottom end of the filter chamber. A spring 335 is installed in the cylinder cavity. The top end abuts against the cover plate 362, and the bottom end abuts against the top cover 333.

[0058] The top of the sliding cylinder 331 extends into the cylinder cavity and is slidably connected to it, ensuring its sliding motion within the cavity. The liquid outlet 337 on the sliding cylinder 331 ensures communication with the liquid transfer port 363 on the fixed cylinder 361. The filter cylinder 332 is fixedly connected to the bottom end of the sliding cylinder 331, ensuring the formation of the filtration chamber. The annular plate 336 on the sliding cylinder 331 abuts against the sliding sleeve 34, ensuring a seal on the inner cavity of the sliding sleeve 34. The suction pipe 334 ensures that all liquid inside the filtration chamber is extracted, preventing any residue from remaining. The spring 335 ensures that after the sliding sleeve 34 descends, the top cover 333 pushes the sliding cylinder 331 and filter cylinder 332 downwards promptly, ensuring communication between the liquid outlet 337 and the liquid transfer port 363 after cleaning.

[0059] Specifically, to prevent the slide cylinder 331 from traveling too far downwards, an outwardly extending limiting block can be provided at the top of the slide cylinder 331. Correspondingly, a limiting groove is provided at the top of the cavity of the fixed cylinder 361. When the limiting block moves to the lowest end of the limiting groove, it connects the liquid outlet 337 and the liquid transfer outlet 363. (See [reference needed]). Figure 5 and Figure 6 .

[0060] In this embodiment, the slide cylinder 331 and the cylinder cavity are clearance fit, and the upper and lower sides of the corresponding liquid transfer port 363 are respectively provided with annular seals. The annular seals are provided on the inner wall of the fixed cylinder 361 to ensure the communication between the liquid transfer port 363 and the liquid flow port 337.

[0061] In some embodiments, the unidirectional air intake structure 37 described above can be adopted as follows: Figures 5 to 6 The structure shown. See figure. Figures 5 to 6Each unidirectional air intake structure 37 includes an intake pipe 371, a sealing ball 372, and an elastic element 373. The intake pipe 371 is fixed to the cover plate 362, and a fixing ring is provided in the intake pipe 371 at a distance from the cover plate 362. The sealing ball 372 is disposed between the fixing ring and the cover plate 362. The elastic element 373 is disposed between the fixing ring and the cover plate 362 and abuts against the sealing ball 372, and can continuously push the sealing ball 372 to keep the sealing ball 372 blocking the air vent.

[0062] The one-way air intake structure 37 can prevent the entry of filtered liquid and ensure that it only opens after the slide 331 moves upward. This ensures that the backwashing and filtration operations can be carried out independently. The structure is simple and highly practical.

[0063] In some embodiments, the sealing structure 38 described above may employ, for example... Figure 3 The structure shown. See also Figure 3 Each sealing structure 38 includes a baffle 381 and a telescopic structure 382. The baffle 381 is hinged to the bottom end of the sliding sleeve 34, and a fixed pull rod is provided on the baffle 381, with one end of the fixed pull rod extending obliquely. The fixed end of the telescopic structure 382 is hinged to the sliding sleeve 34, and the telescopic end is hinged to the extended end of the fixed pull rod, which can drive the baffle 381 to pitch and rotate.

[0064] The telescopic structure 382 drives the fixed pull rod, which in turn drives the baffle 381 to tilt and rotate, ensuring the opening and closing of the bottom opening of the sliding sleeve 34, so as to ensure the rapid discharge of the filter residue inside.

[0065] In some embodiments, the driving structure 35 described above may adopt the following... Figures 2 to 4 The structure shown. See also Figures 2 to 4 Each drive structure 35 includes a rectangular frame 351 and a hydraulic cylinder 352. The rectangular frame 351 has a rectangular opening through which the corresponding sliding sleeves 34 pass, and the length direction of the rectangular opening is set along the second direction. There are two hydraulic cylinders 352, which are respectively set on both sides of the housing 32 along the second direction and are both mounted on the support frame 31. The telescopic end of each hydraulic cylinder 352 is fixedly connected to the rectangular frame 351.

[0066] The rectangular frame 351 allows for the simultaneous movement of multiple sliding sleeves 34, thus ensuring the simultaneous cleaning of multiple filter element structures 33 and improving cleaning efficiency. Furthermore, the rectangular frame 351 is easy to manufacture. Two hydraulic cylinders 352 ensure the stability of the rectangular frame 351's movement.

[0067] Specifically, each sliding sleeve 34 has a limiting groove at its bottom that limits the rectangular frame 351 along the vertical direction. Preferably, each sliding collar may have two sets of limiting components at its bottom end, with each set of limiting components spaced apart around the axis of the sliding sleeve 34. Each set of limiting components includes two limiting plates spaced apart along the vertical direction, which together form a limiting groove for the long side of the rectangular frame 351 to be fitted.

[0068] In some embodiments, the filter 30 described above may employ, for example... Figures 2 to 4 The structure shown. See also Figures 2 to 4 The filter 30 also includes a receiving hopper 39, which is located below each sliding sleeve 34. The receiving hopper 39 is designed to receive the filter residue discharged from each sliding sleeve 34. The receiving hopper 39 can be movable to ensure the transfer of filter residue.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A back-end processing system for metal recovery from fly ash of municipal solid waste incineration, characterized in that, The device includes a reaction vessel connected to a leachate storage tank, a dosing unit connected to the reaction vessel for adding metallic zinc, a filter connected to the reaction vessel, an extraction unit connected to the filter, a wastewater treatment device connected to the extraction unit, an electrolysis unit connected to the extraction unit, and a grinding device located in the electrolysis unit and the grinding device. The filter has a slag outlet for discharging a mixture of copper, cadmium and lead, and a liquid outlet for discharging a zinc chloride solution and communicating with the extraction unit. The grinding equipment is used to grind a portion of the blocky elemental zinc obtained from the electrolysis unit, so as to feed it back into the dosing unit.

2. The back-end processing system for metal recovery from municipal solid waste incineration fly ash as described in claim 1, characterized in that, The grinding equipment is a ball mill.

3. The back-end processing system for metal recovery from municipal solid waste incineration fly ash as described in claim 1, characterized in that, The filter includes a support frame, a housing, filter element structures, a sliding sleeve, and a drive structure. The housing is mounted on the support frame and has a receiving cavity and a liquid inlet communicating with the receiving cavity. The top of the housing is provided with multiple sets of spaced-apart drainage modules. The spacing direction of each drainage module is defined as a first direction, and the horizontal direction perpendicular to the first direction is defined as a second direction. Each set of drainage modules includes multiple liquid transfer structures spaced along the second direction. Each liquid transfer structure is connected to the extraction unit via a liquid transfer pipeline. Each liquid transfer structure is also provided with a unidirectional air inlet structure. Multiple filter element structures are provided, each corresponding to one of the liquid transfer structures. Each filter element structure is arranged along... The filter element is vertically slidably disposed in the accommodating cavity, with its top end extending into the corresponding liquid transfer structure. The filter element structure has a liquid outlet that can communicate with the liquid transfer port on the liquid transfer structure. Multiple sliding sleeves are provided, each slidingly disposed at the bottom of the housing and corresponding to each liquid transfer structure. The top end of each sliding sleeve is located in the accommodating cavity, and the bottom end is located below the housing. The bottom end of each sliding sleeve has a sealing structure. Multiple driving structures are provided, each driving structure corresponding to each group of drainage modules. Each driving structure is connected to the bottom of multiple sliding sleeves corresponding to each group of drainage modules, used to drive each sliding sleeve to move up and down. Each of the driving structures drives the corresponding sliding sleeves to move upwards and fit over the outside of the corresponding filter element structure. Subsequently, each sliding sleeve abuts against the annular plate on the corresponding filter element structure and pushes the filter element structure upwards to disconnect the liquid outlet and liquid transmission outlet. At the same time, the one-way air inlet structure is opened to backwash the filter element structure.

4. The back-end processing system for metal recovery from municipal solid waste incineration fly ash as described in claim 3, characterized in that, Each of the liquid transfer structures includes a fixed cylinder and a cover plate; the fixed cylinder is fixed to the top of the housing and has a cylindrical cavity arranged vertically and communicating with the receiving cavity; the liquid transfer port is located on the side wall of the fixed cylinder; the cover plate is detachably connected to the top of the fixed cylinder and the cover plate is provided with an air hole communicating with the one-way air inlet structure.

5. The back-end processing system for metal recovery from municipal solid waste incineration fly ash as described in claim 4, characterized in that, Each filter element structure includes a slide cylinder, a filter cylinder, a top cover, a liquid extraction tube, and a spring. The slide cylinder is slidably connected to the top of the housing in a vertical direction, with its top end extending into the corresponding cylinder cavity and its bottom end located in the receiving cavity. The annular plate is fitted onto the bottom of the slide cylinder. The liquid outlet is located on the side wall of the slide cylinder. The filter cylinder is arranged in a vertical direction, with its top end fixedly connected to the bottom end of the slide cylinder. The filter cylinder and the slide cylinder together form a filtration cavity. The top cover is fixed to the top of the slide cylinder and has multiple air holes and a pin corresponding to the one-way air inlet structure. The liquid extraction tube is located in the filtration cavity, with its top end connected to the slide cylinder and communicating with the liquid outlet, and its bottom end extending to the bottom end of the filtration cavity. The spring is located in the cylinder cavity, with its top end abutting against the cover plate and its bottom end abutting against the top cover.

6. The back-end processing system for metal recovery from municipal solid waste incineration fly ash as described in claim 4, characterized in that, Each of the unidirectional air intake structures includes an air intake pipe, a sealing ball, and an elastic element; the air intake pipe is fixed to the cover plate, and a fixing ring is provided in the air intake pipe at a distance from the cover plate; the sealing ball is disposed between the fixing ring and the cover plate; the elastic element is disposed between the fixing ring and the cover plate and abuts against the sealing ball, for continuously pushing the sealing ball so that the sealing ball keeps blocking the air hole.

7. The back-end processing system for metal recovery from municipal solid waste incineration fly ash as described in claim 3, characterized in that, Each of the sealing structures includes a baffle and a telescopic structure; the baffle is hinged to the bottom end of the sliding sleeve, and a fixed pull rod is provided on the baffle, with one end of the fixed pull rod extending obliquely; the fixed end of the telescopic structure is hinged to the sliding sleeve, and the telescopic end is hinged to the extended end of the fixed pull rod, for driving the baffle to pitch and rotate.

8. The back-end processing system for metal recovery from municipal solid waste incineration fly ash as described in claim 3, characterized in that, Each of the drive structures includes a rectangular frame and a hydraulic cylinder; the rectangular frame has a rectangular opening through which the corresponding sliding sleeve passes, and the length direction of the rectangular opening is set along the second direction; there are two hydraulic cylinders, which are respectively set on both sides of the housing along the second direction and are both set on the support frame, and the telescopic end of each hydraulic cylinder is fixedly connected to the rectangular frame; Each of the sliding sleeves has a limiting groove at its bottom that limits the rectangular frame along the vertical direction.

9. The back-end processing system for metal recovery from municipal solid waste incineration fly ash as described in claim 3, characterized in that, The filter also includes a receiving hopper located below each of the sliding sleeves.

Images